Effect of curcumin on the expression of ahyI/R quorum sensing genes and some associated phenotypes in pathogenic Aeromonas hydrophila fish isolates.

Quorum sensing (QS) in Aeromonas hydrophila is mainly based on the modulation of ahyI/R genes that regulates bacterial virulence determinant phenotypes. The use of QS inhibitors would be of particular interest in inhibiting bacterial pathogenicity and infections. In this study, we aimed to determine the effect of curcumin, a natural component of Curcuma longa, on the expression of QS regulating genes, ahyI and ahyR, as well as some QS regulated virulence characteristics in pathogenic fish isolated A. hydrophila strains. The minimum inhibitory concentration (MIC) of curcumin against bacteria was determined using the broth micro-dilution method and the expression of quorum sensing genes ahyI and ahyR among the bacteria treated with curcumin was determined using quantitative polymerase chain reaction (qPCR). Also, the effect of curcumin on some QS associated traits, including biofilm formation, swarming and swimming motility, proteolytic potential, and bacterial hemolytic activity was investigated. According to the results, curcumin, at a concentration of 32 µg/mL, significantly reduced the expression of both ahyI and ahyR genes among bacterial strains up to 64.2 and 91.0%, respectively. Moreover, curcumin efficiently inhibited bacterial biofilm formation, swimming, and swarming motility. Also, bacterial proteolytic activity was slightly reduced, while hemolytic activity was not significantly affected. This study demonstrated the use of curcumin to attenuate ahyI/R QS genes and several QS associated phenotypes in A. hydrophila. These findings indicate the therapeutic potential of curcumin as an anti-QS agent, to be used against A. hydrophila pathogenesis in aquaculture.

Potential KPC-2 carbapenemase reservoir of environmental Aeromonas hydrophila and Aeromonas caviae isolates from the effluent of an urban wastewater treatment plant in Japan.

Aeromonas hydrophila and Aeromonas caviae adapt to saline water environments and are the most predominant Aeromonas species isolated from estuaries. Here, we isolated antimicrobial-resistant (AMR) Aeromonas strains (A. hydrophila GSH8-2 and A. caviae GSH8M-1) carrying the carabapenemase blaKPC-2 gene from a wastewater treatment plant (WWTP) effluent in Tokyo Bay (Japan) and determined their complete genome sequences. GSH8-2 and GSH8M-1 were classified as newly assigned sequence types ST558 and ST13, suggesting no supportive evidence of clonal dissemination. The strains appear to have acquired blaKPC-2 -positive IncP-6-relative plasmids (pGSH8-2 and pGSH8M-1-2) that share a common backbone with plasmids in Aeromonas sp. ASNIH3 isolated from hospital wastewater in the United States, A. hydrophila WCHAH045096 isolated from sewage in China, other clinical isolates (Klebsiella, Enterobacter and Escherichia coli), and wastewater isolates (Citrobacter, Pseudomonas and other Aeromonas spp.). In addition to blaKPC-2 , pGSH8M-1-2 carries an IS26-mediated composite transposon including a macrolide resistance gene, mph(A). Although Aeromonas species are opportunistic pathogens, they could serve as potential environmental reservoir bacteria for carbapenemase and AMR genes. AMR monitoring from WWTP effluents will contribute to the detection of ongoing AMR dissemination in the environment and might provide an early warning of potential dissemination in clinical settings and communities.

A fatal diarrhoea outbreak in farm-raised Deinagkistrodon acutus in China is newly linked to potentially zoonotic Aeromonas hydrophila.

Deinagkistrodon acutus is a venomous pit viper commonly used in traditional Chinese medicine; farming these snakes has become a major industry. In 2017, an outbreak of fatal diarrhoea among farm-raised D. acutus in Hunan Province caused the deaths of 5,600 snakes within 3 weeks. We isolated a brand-new sequence type of Aeromonas hydrophila (ST516) from lesions and confirmed that this bacterium was the causal agent of the outbreak. Snakes infected with the bacterium in the laboratory showed similar clinical symptoms to those of snakes in the original outbreak. We also tested bacterial virulence in Kunming mice to examine the likelihood of zoonosis. Isolates were pathogenic to mice, causing diarrhoea within 4 hr post-challenge, which indicates that the bacterium can potentially infect mammals. Environmental analysis showed that polluted spring water likely caused the diarrhoea in snakes. This study is the first to report on a large-scale outbreak of fatal diarrhoea in farm-raised snakes, originating in a pathogen that can infect mammals. These results should raise awareness regarding potential anthropozoonosis among poikilotherms, mammals, and humans; appropriate prevention or control methods should be developed.

Ceftriaxone-Resistant Aeromonas hydrophila Infection Following Leech Therapy: A New Resistant Strain.

We report a case of ceftriaxone-resistant Aeromonas hydrophila infection in a 32-year-old man after medicinal leech therapy. The patient underwent a free gracilis muscle flap for dorsal foot soft tissue reconstruction. Because of persistent congestion after venous revision, medicinal leech therapy was initiated to aid in flap salvage. Intravenous ceftriaxone was administered prior to application of leeches for prophylaxis against A. hydrophila. Leech therapy was discontinued after 1 week, and ceftriaxone was discontinued 24 hours thereafter. An infection developed despite being on appropriate antibiotics. Culture sensitivities indicated that A. hydrophila was resistant to ceftriaxone.

Melaleuca alternifolia essential oil prevents alterations to purinergic enzymes and ameliorates the innate immune response in silver catfish infected with Aeromonas hydrophila.

Aeromonas hydrophila infection represents a major impediment to the development of aquaculture, leading to important economic losses. Over the last few years, different methods have been used to counteract and minimize the negative effects of this infection, such as the use of Melaleuca alternifolia essential oil, popularly known as tea tree oil (TTO), that possess a bactericide action against A. hydrophila. The purinergic system develops an important role in the inflammatory response, principally due to involvement of adenosine triphosphate (ATP) in the inflammatory process, as well as by the anti-inflammatory properties of adenosine (Ado), a molecule that is controlled by NTPDase, 5'-nucleotidase and adenosine deaminase (ADA) enzymes. Thus, the aim of this study was to investigate the involvement of purinergic enzymes in the pathogenesis of A. hydrophila infection, and whether the purinergic pathway and innate immune response are involved in the protective effects of TTO in silver catfish (Rhamdia quelen) experimentally infected with A. hydrophila. Our results revealed that A. hydrophila infection increased seric NTPDase and 5'-nucleotidase activity, while ADA activity decreased. Also, the seric levels of pro-inflammatory cytokines such as interleukin-1 (IL-1), IL-6, tumor necrosis factor alpha (TNF-α) and interferon gamma (INF-γ) increased in the infected fish, while the seric level of anti-inflammatory interleukin-10 (IL-10) decreased. Treatment with TTO was able to prevent the impairment of purinergic enzymes and improve the innate immune response through the modulation of cytokine response during A. hydrophila infection. In summary, prophylactic therapy with TTO can be considered an important approach to improve the immune response and consequently avoid the inflammatory process in fish infected with A. hydrophila.

Macroalgal activity against multiple drug resistant Aeromonas hydrophila: A novel treatment study towards enhancement of fish growth performance.

OBJECTIVE: The aim of this study was to evaluate the efficiency of macroalgal extracts as antibacterial agent against multidrug-resistant (MDR) bacteria isolated from Nile tilapia (Oreochromis niloticus) as well as to enhance the fish growth performance by macroalgae diet application. METHODS: A total of 50 swabs were collected from the diseased organs of tilapia fish including gills, skin, spleen, intestine, liver, kidney and muscle. The isolated bacteria were identified and then confirmed by using VITEK 2. Eight macroalgal species were collected from Abu-Qir, Alexandria coast, Egypt. After determination of their biomass, three solvents were used to prepare algal extracts. The antibacterial activities of different macroalgal extracts were measured against MDR Aeromonas hydrophila 6 (MDRAH6) using well-diffusion method. The mechanism by which macroalgal extract affects MDR bacteria was conducted by using transmission electron microscope (TEM). To evaluate the safety of the promising algal extract, GC-MS was performed to detect the composition of S. vulgare extract. In addition, growth performance was measured as an application of algal extracts into fish feed. RESULTS: Between eight collected macroalgal species, Sargassum vulgare showed the highest biomass production (53.4 g m-2). In addition, its ethanolic extract showed the highest significant antibacterial activity with MIC value of 250 µg ml-1. TEM examination showed distinctive changes in the treated MDRAH6 cells including rupture of the cell wall, leakage of cytoplasmic contents, alterations in the cytoplasm density in addition to totally cell deformation. In addition, GC-MS analysis revealed eleven identified components in S. vulgare ethanolic extract, in which 9,12-octadecadienoyl chloride and hexadecanoic acid methyl ester were dominant (46.6 and 19.7 %, respectively). Furthermore, dietary replacement of fish meal with S. vulgare ethanolic extract significantly enhanced the growth performance and survival of Nile tilapia with a significant reduction in the total bacterial count. CONCLUSION: Ethanol extract of the brown macroalga S. vulgare could be a promising antibacterial and a new active agent against MDR A. hydrophila, which could be a major causative agent of Nile tilapia fish diseases. In addition, this study recommended S. vulgare as a natural and effective source to enhance the growth performance of Nile tilapia. In fact, isolation and examination of the individual antibacterial active compounds of the S. vulgar ethanolic extract are under investigation.

Ascophyllum nodosum in the diet of tilapia (Oreochromis niloticus) and its effect after inoculation of Aeromonas hydrophila / Ascophyllum nodosum na dieta de tilapia (Oreochromis niloticus)e o efeito dela depois da inoculação com Aeromonas hydrophila

The objective of this study was to evaluate the effect of Ascophyllum nodosum brown seaweed meal (FAM) on the health of Nile tilapia submitted to inoculation with Aeromonas hydrophila. The experiment was conducted for a period of 40 days using 120 Nile tilapia fingerlings, with age of 40 days, distributed in 20 tanks. A diet including Ascophyllum nodosum seaweed meal at 20g.kg-1 and a control diet (without FAM) were provided which constituted the treatments. Thirty days after beginning the experiment, A. hydrophila was inoculated by bacterial inoculum diluted in sterile saline solution at a concentration of 10(6) CFU ml-1. Except for the width, which was greater for the treatment with the provision of FAM (P<0.05), there was no influence on the performance parameters of the fingerlings, but the occurrence of lesions in animals inoculated with A. hydrophila and fed with FAM was lower and they also exhibited a decline in the lesions in a shorter period of time than the control group. FAM prevents hepatopancreatic congestion in infected animals. Ascophyllum nodosum brown seaweed meal reduced the number of lesions in fish in a shorter time when compared to the control group.

O objetivo desse estudo foi avaliar o efeito da farinha de alga marinha marrom Ascophyllum nodosum (FAM) em alevinois de tilápias do Nilo sob desafio sanitário com inoculação de Aeromonas hydrophila. O experimento foi realizado durante um período de 40 dias com a utilização de 120 alevinos de tilápia do Nilo, distribuídos em 20 aquários. Foi fornecida uma ração com inclusão da farinha da alga marinha Ascophyllum nodosum a 20g.kg ração-1 e uma ração testemunha (sem FAM), que constituiram os tratamentos. Após 30 dias experimentais foi realizada a inoculação de Aeromonas hydrophila por meio de um preparado de inóculo bacteriano com diluição em solução salina estéril a concentração de 106 UFC/ml. Exceto para a largura, que foi maior para o tratamento com o fornecimento da FAM (P<0,05), não houve influência sobre parâmetros de desempenho dos alevinos, mas a ocorrência de lesões nos animais inoculados com A. hydrophila e alimentados com FAM foi menor e, eles também exibiram um declínio das lesões em um menor período de tempo em relação ao grupo controle. FAM impediu a congestão hepatopancreática em animais infectados. A farinha de alga marinha marrom Ascophyllum nodosum reduziu o número de lesões nos peixes em menor tempo quando comparado ao controle.

Bacteremia due to Aeromonas hydrophila in acute lymphoblastic leukemia.

Aeromonas hydrophila (A. hydrophila) is a low virulent organism but may cause devastating fatal infections in immunocompromised host especially in liver cirrhosis. It is rarely reported to cause septicemia in a patient with Acute Lymphoblastic Leukemia (ALL). The mortality rate of septicemia due to A. hydrophila is 29% to 73%. We report a case of 59-year-old female patient who was a known case of ALL, presented with the complaints of fever, lethargy and generalized weakness for one month. After taking blood samples for investigations, empirical antimicrobial therapy was started. She did not improve after 48 hours of therapy. Meanwhile blood culture revealed pure growth of A. hydrophila. After sensitivity report was available, ciprofloxacin was started. Patient became afebrile after 48 hours of treatment with ciprofloxacin. It is very vital to correctly identified and treat bacteremia due to A. hydrophila especially in the underlying leukemic patient.

The role of leech water sampling in choice of prophylactic antibiotics in medical leech therapy.

Medical leech therapy (MLT) with Hirudo medicinalis is well established as a treatment for venous congestion of tissue flaps, grafts, and replants. Unfortunately, this treatment is associated with surgical site infections with bacterial species, most commonly Aeromonas hydrophila, which is an obligate symbiot of H. medicinalis. For this reason, prophylactic antibiotics are recommended in the setting of MLT. After culturing Aeromonashydrophila resistant to ciprofloxacin from a tissue specimen from a patient with a failed replant of three digits post-MLT, we performed environmental surveillance cultures and antibiotic susceptibility testing on water collected from leech tanks. This surveillance was performed twice weekly for 2.5 months. Fourteen surveillance cultures demonstrated 21 isolates of Aeromonas species, 71.4% of which were ciprofloxacin susceptible. All isolates were sulfamethoxazole-trimethoprim (SXT) susceptible. The prophylactic antibiotic regimen of choice for leech therapy at our institution is SXT, with culture of tank water to refine antimicrobial choice if necessary. This study demonstrates the importance of regular surveillance to detect resistant Aeromonas species in medical leeches; however optimal practice has not been established.

Ciprofloxacin-resistant Aeromonas hydrophila cellulitis following leech therapy.

We report a case of surgical site infection with ciprofloxacin-resistant Aeromonas hydrophila following leech therapy. Antimicrobial and genetic analyses of leech and patient isolates demonstrated that the resistant isolates originated from the leech gut microbiota. These data suggest that ciprofloxacin monotherapy as a prophylaxis regimen prior to leech therapy may not be effective in preventing infection.

Acute postoperative infection with Aeromonas hydrophila after using medical leeches for treatment of venous congestion.

INTRODUCTION: Venous convulsion after reconstructive microsurgery procedures is one major complication a surgeon has to deal with. Today, especially in the field of reconstructive microsurgery, medicinal leech therapy enjoys a renaissance. The potential risks such as infections associated with leech therapy are generally underestimated and not sufficiently discussed in literature. METHOD/PATIENTS: We present five male patients with an average age of 47 years. All patients suffered from a trauma incident, which had to be treated as an emergency. Three patients showed, postoperatively, a venous congestion after the reconstructive procedures. Another two patients with flap reconstruction and flap training developed venous problems after 12 and 14 days. In all five cases, the indication was given to use medical leeches (Hirudo medicinalis). In all the patients, a local infection of the injured extremity could be regarded after beginning with the leech treatment. The treatment duration with medical leeches for postoperative venous congestion was an average of 6 days. RESULTS: The reconstructive procedures in all five cases were unfortunately unsuccessful as major local infections were observed. Microbiological analyses showed, in all cases, an infection with Aeromonas hydrophila. CONCLUSION: We recommend making a considered indication for leech therapy, to diagnose wound infections early and to think about prophylactic antibiotics in patients with leech application.

[Leech-borne infection on a TRAM flap: a case report]. / Complication infectieuse d'un lambeau de TRAM liée aux sangsues: à propos d'un cas.

Leeches are used worldwide to treat venous congestion of flaps. Aeromonas hydrophila infections are recognized complications of leech use. We report a new case of delayed leech-borne infection in mammary reconstruction by a Transverse Rectus Abdominis Myocutaneous flap (TRAM), which caused the flap loss. The use of prophylactic antibiotics is a way to prevent A.hydrophila infection (third generation cephalosporin, ciprofloxacin). This antibioprophylaxy must be followed until wound closure of the venous congested tissue.

Aeromonas hydrophila ecthyma gangrenosum without bacteraemia in a diabetic man: the first case report in Italy.

Ecthyma gangrenosum is a well recognized cutaneous manifestation of severe, invasive infection by Pseudomonas aeruginosa usually in immunocompromised and critically ill patients. This type of infection is usually fatal. Aeromonas infection is infrequently reported as the cause of ecthyma gangrenosum. Here we show the first case described in Italy of Aeromonas hydrophila ecthyma gangrenosum in the lower extremities in an immunocompetent diabetic without bacteraemia. A 63-year-old obese diabetic male was admitted with an ulcer on his left leg, oedema, pain and fever. Throughout his hospitalization blood cultures remained sterile, but a culture of A. hydrophila was isolated following punctures from typical leg pseudomonal-ecthyma gangrenosum lesions developed after admission. The patient, questioned again, stated that a few days before he had worked in a well near his house without taking precautions. We conclude that early diagnosis and suitable antibiotic therapy are important for the management of ecthyma gangrenosum. The typical presentation of soft tissue infection of A. hydrophila should mimic a Gram-positive infection, which may result in a delay in administration of appropriate antibiotics. Moreover, A. hydrophila should be considered a possible agent for non-pseudomonal ecthyma gangrenosum in a diabetic man with negative blood cultures, in presence of anamnestical risk factors.

Challenge of pacu (Piaractus mesopotamicus) fed diets supplemented with vitamins C and E by Aeromonas hydrophila under different temperature / Desafio de pacus (Piaractus mesopotamicus) alimentados com dietas suplementadas com vitaminas C e E desafiados por Aeromonas hydrophila em diferentes temperaturas

Pacu Piaractus mesopotamicus fed diets supplemented with three vitamins C and E levels (zero, 250, and 500mg vitamin/kg diet) were challenged with Aeromonas hydrophila under different temperatures. Fish were kept in 300L plastic tanks and fed during the first 60 days with diets without vitamins C and E, in an attempt to reduce vitamin sources. After this period, fish were maintained at an initial density of 14 fish/tank and test diets were offered during 60 days. At the end of the experiment, all fish were infected with 6×10(6)CFU of A. hydrophila/fish, intraperitoneally injected. No interaction of dietary levels of vitamin C vs. E on mortality was observed. Supplementation with vitamins C and E did not decrease the mortality rate of fish challenged with A. hydrophila. Regardless of vitamin supplementation, after challenge, smaller fish showed higher mortality than larger ones and the fish group maintained in an environment under higher temperatures showed higher mortality rate.

Pacus Piaractus mesopotamicus alimentados com dietas contendo três níveis de vitaminas C e E (zero, 250 e 500mg/kg de ração) foram desafiados, em diferentes temperaturas, com Aeromonas hydrophila. Os peixes foram mantidos em caixas plásticas de 300L e, com o objetivo de reduzir as reservas vitamínicas, durante os primeiros 60 dias, foram alimentados com dietas isentas das vitaminas C e E. Após esse período, os peixes foram estocados na densidade inicial de 14 peixes/caixa e as dietas-teste foram oferecidas durante 60 dias. Ao final do experimento, todos os peixes foram infectados com 6×10(6) UFC de A. hydrophila/peixe, injetada intraperitonealmente. Não houve interação nível de vitamina C vs. nível de vitamina E quanto à mortalidade. A suplementação com as vitaminas C e E não reduziu a taxa de mortalidade dos peixes desafiados com A. hydrophila. Independentemente da suplementação vitamínica, após o desafio, os peixes menores apresentaram maior taxa de mortalidade que os maiores e o grupo mantido em ambiente com temperatura mais alta apresentou maior taxa de mortalidade após o desafio.

A possible new cause of spa bath folliculitis: Aeromonas hydrophila.

A 34-year-old man presented with a pubic eruption of 4 weeks duration, affecting both himself and his partner. He had been treated unsuccessfully with intravenous and oral dicloxacillin. The eruption was a severely inflammatory folliculitis, with haemo-serous exudate and marked oedema. A clinical diagnosis of herpes simplex virus folliculitis was disproved when routine bacteriology isolated Aeromonas hydrophila and multiple viral polymerase chain reaction studies were negative. Histology demonstrated a chronic folliculitis with no organisms present. Both he and his partner were treated with oral ciprofloxacin 500 mg bd for 6 weeks with clinical clearance of infection, but both developed a scarring alopecia. Infection was attributed to possible contamination of a poorly maintained home spa bath with A. hydrophila.

Bacteriological investigation of the occurrence and antibiotic sensitivities of the gut-flora of the potential southern African medicinal leech, Asiaticobdella buntonensis (Hirudinidae).

The lack of availability of medicinal leeches is a major impediment to the widespread use of leech therapy for treatment of congested flaps and replants in southern Africa. An investigation into the suitability of an alternative leech, the indigenous southern African leech, Asiaticobdella buntonensis, was therefore started. The risk of hospital-acquired infection related to the use of leeches and the antibiotic sensitivities of bacteria isolated from the gastro-intestinal tract of wild-caught leeches were investigated. Eleven bacterial genera were isolated but Aeromonas were most frequently isolated, occurring in 82% of microbiological samples. All were sensitive to cefotaxime and amikacin. The gut-flora and their sensitivities to 19 antibiotics were similar to those reported for the traditional medicinal leech, Hirudo medicinalis. These results emphasize the need to anticipate unusual infections when prescribing prophylactic or curative antibiotics in the course of leech therapy.

Aeromonas hydrophila infections following use of medicinal leeches in replantation and flap surgery.

Aeromonas hydrophila infections are a recognized complication of postoperative leech application, and can occur with measurable frequency in populations of patients treated with leeches. We review 11 previously reported leech-related Aeromonas infections and analyze seven unreported cases. These infections range from minor wound complications to extensive tissue loss and sepsis. Often, these infections followed leech application to tissue with questionable arterial perfusion. Onset of clinical infection in these patients ranged from within 24 hours of leech application to 10 days or more after leech application. Late infections may represent bacterial invasion from colonized necrotic tissue. Based on these observations, we recommend that leech applications be restricted to tissue with arterial perfusion to minimize contamination of necrotic tissue. We also recommend that patients treated with leeches receive antibiotics effective against Aeromonas hydrophila before leech application. Patients treated with leeches and discharged with eschars or open wounds might benefit from oral antibiotic therapy until wound closure. These precautions may minimize or eliminate this complication of leech use.

Postprandial Aeromonas hydrophila cultures and antibiotic levels of enteric aspirates from medicinal leeches applied to patients receiving antibiotics.

Increasing use of medicinal leeches has been accompanied by increasing numbers of reports of Aeromonas hydrophila infections after leech application on or near damaged tissue. We examined the enteric contents of postprandial leeches after their application to patients receiving antibiotics. We found measurable levels of antibiotic in the leech enteric contents, and in leeches applied to patients receiving an antibiotic effective against Aeromonas hydrophila, there was a significant decrease in positive Aeromonas enteric cultures. Suppression of leech enteric bacteria by antibiotic administration to the patient may be an effective strategy to prevent invasive infection by Aeromonas hydrophila as well as bacterial colonization of devitalized tissue that could be the source of late infection. Clinical studies will be required to clarify whether suppression of leech enteric flora results in a decrease in infections associated with leech use.

The use of medicinal leeches in the salvage of flaps with venous congestion.

The use of medicinal leeches (Hirudo medicinalis) for the salvage of tissues with venous congestion has been intermittent over the last two centuries. During the last decade, interest in leech therapy has undergone a resurgence. Hirudo's tricuspid bite injects a highly potent anticoagulant. The site usually bleeds for 1 to 2 hours and under special circumstances may bleed for up to 24 hours. This collective series presents four patients in whom immediate postoperative venous congestion threatened the survival of three tissue replants and one latissimus dorsi flap. Two of the replants were completely salvaged; the other two failed due to infection. Hirudo medicinalis is an important adjunct in preventing flap or replant failure secondary to venous congestion, but its use is associated with significant risks.